DARPA Influence
After the invention of RISC-V, many projects used it, including research programs funded by the Defense Advanced Research Projects Agency (
DARPA), in many places and many companies. Open source standards provide great benefits to U.S. taxpayers in reducing the cost of advanced military system development, and also increases security by allowing the government to build their own trusted implementations at low cost. Note that several decades ago, the United States Air Force developed the open standard MIL-STD-1750 16-bit processor ISA for military applications for the same reasons (
https://en.wikipedia.org/wiki/MIL-STD-1750A).
The UC Berkeley
ASPIRE Lab succeeded the Par Lab, and was led by Krste Asanović. It lasted from 2013 to 2018 and led to the building of several RISC-V compatible microprocessors. It had funding from DARPA as well as from many companies. The DARPA funding was
basic research funding (6.1 category).
Basic research funding to universities is largely for unrestricted research with permission to publically disseminate the results. This contract is the standard model for U.S. federal grants to universities, and allows for results from the funded work to be published in the open literature and made accessible to the public at large, worldwide. The government retains rights to use any technology developed in the research, but, unless explicitly stated, does not restrict the technology.
A related DARPA photonics program predates RISC-V and funded research at MIT in 2006. The research supported the development of integrated silicon photonics. Later stages of funding at MIT and Berkeley were used to build prototype chips, which included RISC-V cores as infrastructure to demonstrate the photonic links.
The ASPIRE Lab was funded by the DARPA Power Efficiency Revolution for Embedded Computing Technologies (PERFECT)program. The goal of the program was to develop revolutionary approaches as well as the technologies and techniques to provide the power efficiency required to enable embedded computing systems. Researchers used RISC-V based systems to demonstrate the ideas in that program.
In all of these funded projects, the RISC-V ISA specification and RISC-V open-source cores were not a contract deliverable. RISC-V was just the infrastructure separately developed to support the funded research.
While DARPA did not fund the original RISC-V ISA definition, DARPA funding played a significant role in its later development. The linked
article on the SSITH Voting Machine and
DOD presentation by Linton Salmon detail some of the areas where DARPA research continues to support RISC-V.
DARPA is currently funding a large set of programs around open-source hardware technology. RISC-V International has never had DARPA funding, nor pursued or received funding from any government.